- May 20 - First Council of Nicaea - first "Ecumenical Council" of the Christian Church: The Nicene Creed is formulated, the date of Easter is discussed.
- Gladiatorial combat is outlawed in the Roman Empire.
- The Church of the Nativity is built in Bethlehem
- Jin Cheng Di succeeds Jin Ming Di as emperor of China.
- Procopius, attempted usurper of the Roman Empire (approximate date)
- Ammianus Marcellinus, Roman historian (approximate date)
- Jin Ming Di, emperor of China.